1. Field of the Invention
This invention relates to benzylamine derivatives represented by the general formula (I) ##STR3## wherein
R.sub.1 represents an alkyl group,
R.sub.2 represents a group of the formula ##STR4## in which
R.sub.4 represents a hydrogen atom, a lower alkyl group or a halogen atom, and
R.sub.3 represents an alkyl or alkenyl group, and acid addition salts thereof, and also to antimycotic agents for humans or animals, agricultural fungicides and industrial fungicides or microbicides comprising the above compounds as active ingredients.
2. Background Art
In recent years research and development of antibiotics such as cephalosporin derivatives has rapidly advanced, and many drugs effective for infections by Gram-positive or Gram-negative pathogenic bacteria have been developed and used. On the other hand, in spite of ever-increasing cases of mycosis which are difficult to cure, commercial antimycotic agents have not proved to be entirely satisfactory owing to insufficient effects or the occurrence of side-effects. It has been strongly desired therefore to develop antimycotic agents which are highly safe with reduced side-effects and can produce an outstanding therapeutic effect.
The same can be said with regard to agricultural and industrial fungicides. In recent years, many non-metallic fungicides have been developed in place of inorganic or organic heavy metal compounds having strong toxicity to humans and animals in spite of their high fungicidal effects. These non-metallic fungicides, however, give rise to many problems such as insufficient effects, insufficient residual effects, phytotoxicity and the development of resistant strains. In agriculture, it has been desired to develop fungicides which show outstanding effects against difficult-to-control plant diseases such as gray mold (Botrytis cineria) in cucumber, tomato, etc. in practical dosages and can be safely and easily used.
Only a few compounds, for example benzimidazole compounds (e.g., benomyl, thiophanate methyl) and dicarboximide compounds (e.g., procymidone) are known as agents effective for controlling gray mold. It was already reported in the stage of development work that strains resistant to these agents appeared. Furthermore, cross resistance is observed between benzimidazoles and dicarboximides. Hence, these chemicals cannot be easy-to-use fungicides with stable effects, and there has been a very great demand for the development of chemicals which are effective against this disease which causes a great deal of damage.
Non-metallic industrial fungicides have superseded inorganic or organic heavy metal compounds. But since their effects are limited to a particular range of microorganisms or the range of their application is limited, their fungicidal effects are not sufficient. Such industrial fungicides frequently cannot prevent contamination and biodeterioration of industrial materials and products. For example, benzimidazole-type compounds, which are regarded as the best non-metallic fungicides, exhibit excellent fungicidal activity against such fungi as Aspergillus, Penicillium and Trichoderma by an agar dilution method which occur in paints, pastes, wooden and bamboo products, textiles, etc. and degrade them, but show no fungicidal activity against Alternaria and Mucor which occur on the coated surfaces of emulsion paints, artificial leathers, wall cloths, etc. These benzimidazole compounds show no activity against bacteria. Moreover, their effects cannot be expected in practical dosages (100 to 500 ppm) in many situations of actual use, for example, in anti-fungal treatment of paint films, wall trimming materials and wooden and bamboo products. It has been desired therefore to develop industrial fungicides or microbiocides which exhibits an outstanding effect in practical dosages and yet are safe and easy to use.
Benzylamine derivatives of the following general formula (IX) ##STR5##
wherein X represents a hydrogen or chlorine atom or a methoxy group, which are similar to the compounds of this invention, are disclosed in J. Org. Chem., 12, 760 (1947). This paper reports the results obtained by screening various arylmethylamine derivatives for antimalarial activity. The paper states that no activity is noted in compounds of general formula (IX). Furthermore, it fails to describe any biological activities including antimycotic activity of the compounds (IX).